Bistorta affinis 'Superba'

RHS Plant Profile
knotweed 'Superba'

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knotweed 'Superba' RHS 2002
knotweed 'Superba' visionspictures.com

Synonyms

Polygonum affine 'Dimity'
Persicaria affinis 'Superba'
Polygonum affine 'Superbum'
Persicaria affinis 'Dimity'
Bistorta affinis 'Dimity'

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Herbaceous Perennial Bogs
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A semi-evergreen perennial forming a wide mat to 20cm in height, with dark green, elliptic leaves and erect spikes of small pale pink flowers that deepen to crimson with age

Position

Full sun, Partial shade

Soil Types

Clay, Loam

Max Height

0.1-0.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
5–10 years
Max Spread
0.5-1 metres
Max Height
0.1-0.5 metres

Growing Conditions

Clay Loam
Moisture
Moist but well–drained or Poorly–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
South–facing or North–facing or West–facing or East–facing
Exposure
Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
H7

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Polygonaceae
Native to GB/Ireland
No
Foliage
Semi evergreen
Habit
Matforming
Genus
A genus of herbaceous, rhizomatous perennials with erect, unbranched stems, bearing short terminal spikes of small, white or pink, bell-shaped flowers
Name Status
Accepted

How to Grow

Cultivation

Grow in any moist soil in full sun or partial shade See https://www.rhs.org.uk/plants/trials-awards for further information about RHS plant trials and awards

Propagation

Propagate by division in spring or autumn

Suggested planting locations and garden types

  • Rock garden
  • Cottage and informal garden
  • Flower borders and beds
  • Garden edging
  • Ground cover

Pruning

Cut back after flowering

Pests

Generally pest-free

Diseases

Generally disease-free